Ultrathin, flexible reflective electronic displays that look like print on paper are of great interest as they have potential applications in wearable computer screens, electronic paper, smart identity cards, and electronic signage. Electro-optical display technology, such as electrophoretic or electrokinetic display technology, is an important approach to this type of display medium. In electrophoretic or electrokinetic displays, pixel or segment electrodes, electrodes within the viewing area of a display that are electrically isolated, may control the local position of charged colorant particles in the ink by application of electric fields. The local position of the particles may influence the reflectance of such pixel or segment electrodes. Without subscribing to any particular theory, in electronic inks, particles that exhibit good dispersibility and charge properties in non-polar dispersing media may increase the stability of the ink and may improve the switching behavior of the ink, as further discussed below, which may increase the useful lifetime of the ink. Additionally, use of non-polar dispersing media in the electrophoretic or electrokinetic devices may minimize current leakage.
As noted previously, electrophoretic and electrokinetic displays may have numerous applications. Some display applications, such as e-books and other digital signage applications, do not require updates at the same rate as video display applications. In one example, instead of an update rate measured in fractions of a second, the information displayed in an e-book or another digital signage application may require an update anywhere from every one to two minutes or only once a day. Therefore, if a display does not require constant power to maintain images, it may consume less power when displaying images resulting in power savings and may be more easily remotely deployed.